This invention relates to nuclear fuel storage and in particular to an apparatus for storing fuel assemblies in a pool. U.S. Pat. No. 4,177,385 issued on Dec. 4, 1979 to Frank Bevilacqua for "Nuclear Fuel Storage" discloses an apparatus and method for storage of fuel in a stainless steel, egg-crate frame within a storage pool. Fuel is initially stored in a checkerboard pattern or in each opening if the fuel is of low enrichment. Additional fuel (or fuel of higher enrichment) is later stored by adding box inserts within each opening in the frame, thereby forming flux-traps between the openings. Still higher enrichment fuel is later stored by adding poison material around the boxes.
The method and apparatus described in the Bevilacqua patent can be significantly improved by simplifying the structure of the box inserts and the manner in which poison is added thereto.